diff --git a/game/reconstructed/mech.cpp b/game/reconstructed/mech.cpp
index 0ba05ed..72408ea 100644
--- a/game/reconstructed/mech.cpp
+++ b/game/reconstructed/mech.cpp
@@ -603,6 +603,26 @@ int
 		|| (liveGenerators == 0)
 		|| (coolantFrac < 0.05f)							// _DAT_0049fb50
 		|| (gimped && noviceSim);
+	// (#155 rig) BT_FORCE_EJECT_ARM: pin the panic-arm state without damage
+	// side-effects, so the dead-MFD-bank repro isolates the ModeEject
+	// interaction.  =1 steady ON; =2 CHATTER at the evaluator's own rate
+	// (the authentic no-hysteresis flap, e.g. a coolant fraction hovering at
+	// the 0.05 threshold).  Env-gated bench scaffolding, off by default.
+	{
+		static int s_forceArm = -1;
+		if (s_forceArm < 0)
+		{
+			const char *fa = getenv("BT_FORCE_EJECT_ARM");
+			s_forceArm = (fa != 0) ? atoi(fa) : 0;
+		}
+		if (s_forceArm == 1)
+			ejectPermitted = 1;
+		else if (s_forceArm == 2)
+		{
+			static unsigned s_flap = 0;
+			ejectPermitted = (int)(++s_flap & 1);
+		}
+	}
 	return ejectPermitted;
 }